1. Field of the Invention
The present invention relates generally to a speech recognition system for an automotive vehicle, and more particularly to a speech recognition system provided with means for effectively eliminating noise generated by engines from a spoken phrase signal inputted through a microphone.
2. Description of the Prior Art
There is a well-known speech recognizer which can activate various actuators in response to human spoken instructions. When this speech recognizer is mounted on a vehicle, the headlight, for instance, can be turned on or off in response to spoken instructions such as "Headlight on" or "Headlight off". Such a speech recognizer usually can recognize various spoken instructions in order to control various actuators; however, there are some problems involved in applying this system to an automotive vehicle.
A speech recognizer is usually used in a relatively quiet environment; however, the speech recognition system for an automotive vehicle is typically used in a relatively noisy environment, especially while an engine is running. The speech recognition rate (the percentage of correct recognition of spoken phrase instruction) of the conventional speech recognizer is high in the case where background noise level is low, but low in the case where background noise level is high.
Therefore, when noise generated by an engine exceeds a predetermined level within the passenger compartment, the conventional speech recognizer may not activate the actuator corresponding to a spoken instruction inputted thereto or may activate a different actuator, resulting in an undesirable or even in a dangerous situation.
A more detailed description of a typical speech recognizer will be made with reference to the attached drawing in conjunction with the present invention under DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS.